It has been proposed to mount mail receptacles of various types to a garage door to receive mail passed through a mail slot in the door. However, there is a need for a garage door mail receptacle having simple, inexpensive design that can be installed on any type of garage door, including residential or industrial wood garage doors with half inch or more door wood thickness and composite or metal garage doors with trust support, and is capable of receiving and holding mail when in a vertical mail-holding position (when mounted below the mail slot with the door in a closed, vertical position) and prevents the mail from falling out of the receptacle when the door is opened (i.e., moved from the closed, vertical position to an open, horizontal position). There is also a need for such a garage door mail receptacle that can conveniently folded against a garage door when not in use (for convenience).